dubious
The definition for dubious is "Questionable." Used in a sentence: Karl found Kevin's claim that he was sick dubious, as he had just seen him playing football.
flaw
The definition for flaw is "An imperfection." Used in a sentence: The otherwise perfect diamond had a tiny flaw that reduced its value.
illuminate
The definition for illuminate is "To make clear." Used in a sentence: Her excellent lecture illuminated the complicated subject of nuclear physics.
mundane
The definition for mundane is "Practical, ordinary." Used in a sentence: The flighty Caroline could not be troubled with mundane tasks such as paying her bills.
pretense
The definition for pretense is "False intention or purpose." Used in a sentence: The jewel thief entered the mansion under the pretense of fixing a leaky faucet.